The present invention relates to a chemical analysis apparatus that makes use of a centrifugal force to cause movement, mixing, etc. of a solution, and more particular, to a chemical analysis apparatus that uses a removable cartridge.
As a method of extracting DNA from a liquid specimen containing DNA, JP-A-2003-502656 describes an apparatus for and a method of conducting in vitro amplifying assay as miniaturized. In this apparatus, after a DNA mixing liquid is passed through a glass filter as an inorganic substrate, a washing liquid and an eluant are passed therethrough and only DNA is recovered. The glass filter is provided on a rotatable structure and reagents such as a washing liquid, an eluant, etc. are held in respective reagent reservoirs in the same structure. A centrifugal force generated upon rotation of the structure causes the respective reagents to flow, and valves provided in minute flow channels, which interconnect the respective reagent reservoirs and the glass filter, are opened whereby the reagents pass through the glass filter.
As a chemical analysis apparatus that extracts and analyzes a specific chemical substance, such as a nucleic acid, etc., from a specimen containing a plurality of chemical substances, JP-A-2001-527220 describes an integral type fluid operation cartridge. In this apparatus, an integral type cartridge comprises therein a trap component part that traps reagents such as a solution, a washing liquid, an eluant, etc., and a nucleic acid, and after a specimen containing a nucleic acid is injected into the cartridge, the specimen and the eluant are mixed with each other and passed through the trap component part, a washing liquid is further passed through the trap component part, an eluant is further passed through the trap component part, and the eluant having passed through the trap component part is brought into contact with a PCR reagent to make it flow to a reaction chamber.
However, the apparatus described in the JP-A-2003-502656 involves a possibility that the reagents having passed remain in the valve parts to contaminate the recovered DNA because wax, etc., melting when heated is used for the valves. That is, there is a possibility that a DNA mixing liquid and a washing liquid remain in the valve parts and the DNA mixing liquid and the washing liquid remaining in the valve parts flow into the glass filter during a process, in which a centrifugal force causes an eluant to pass through the glass filter.
Also, with the integral type fluid operation cartridge described in the JP-A-2001-527220, reagents are passed through the trap component part by opening valves, etc. provided in the minute flow channels, which interconnect the respective reagent chambers and the trap component part, when using a pump to feed the respective reagents. Further, valves or the like provided between the trap component part and the respective chambers switch so that, out of reagents having passed through the trap component part, the washing liquid flows to a waste-liquid chamber and the eluant flows to a reaction chamber. In case of feeding a plurality of reagents by means of the pump, the reagents may remain on flow channel walls, and liquids are liable to remain especially when there are present obstacles such as valves, etc. Once the liquids remain, they do not flow, and therefore, there is a possibility of contamination at those parts, at which the liquids join other reagents. Also, in the case where a washing liquid and an eluant, which have passed through the trap component part, are switched over by valves, etc. to make them flow to separate chambers, the washing liquid having earlier flowed to the waste-liquid chamber contaminates flow channels upstream of the valves, etc., for switchover to the reaction chamber, so that there is a fear of mixing of the washing liquid with the eluant.